U.S. patent number 10,826,660 [Application Number 14/725,563] was granted by the patent office on 2020-11-03 for method and apparatus for transmitting and receiving audio data in bluetooth low energy-based wireless communication system.
This patent grant is currently assigned to Samsung Electronics Co., Ltd. The grantee listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Rasmus Abildgren, Sung-Hwan Hyun, Su-Hwan Kim, Tae-Sung Kim, Kook-Hyung Lee.
United States Patent |
10,826,660 |
Hyun , et al. |
November 3, 2020 |
Method and apparatus for transmitting and receiving audio data in
Bluetooth low energy-based wireless communication system
Abstract
A method for transmitting audio data by a master device in a
Bluetooth Low Energy (BLE)-based wireless communication system is
provided. The method includes configuring a data packet to include
identification information indicating whether the audio data is
included in a payload of the data packet and transmitting the data
packet to at least one slave device.
Inventors: |
Hyun; Sung-Hwan (Gyeonggi-do,
KR), Abildgren; Rasmus (Oest, DK), Lee;
Kook-Hyung (Seoul, KR), Kim; Su-Hwan
(Gyeonggi-do, KR), Kim; Tae-Sung (Gyeonggi-do,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Gyeonggi-do |
N/A |
KR |
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Assignee: |
Samsung Electronics Co., Ltd
(KR)
|
Family
ID: |
1000005159439 |
Appl.
No.: |
14/725,563 |
Filed: |
May 29, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150365208 A1 |
Dec 17, 2015 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62010820 |
Jun 11, 2014 |
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Foreign Application Priority Data
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Apr 30, 2015 [KR] |
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10-2015-0062109 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
5/0044 (20130101); H04W 4/80 (20180201); H04L
5/0094 (20130101) |
Current International
Class: |
H04L
5/00 (20060101); H04W 4/80 (20180101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rutkowski; Jeffrey M
Assistant Examiner: Aley; Mehedi S
Attorney, Agent or Firm: The Farrell Law Firm, P.C.
Parent Case Text
PRIORITY
This application claims priority under 35 U.S.C. .sctn. 119(e) to
U.S. Provisional Application Ser. No. 62/010,820, which was filed
in the U.S. Patent and Trademark Office on Jun. 11, 2014, and under
35 U.S.C. .sctn. 119(a) to Korean Patent Application Serial No.
10-2015-0062109, which filed in the Korean Intellectual Property
Office on Apr. 30, 2015, the entire disclosure of each of which are
incorporated herein by reference.
Claims
What is claimed is:
1. A method for transmitting audio data by a master device in a
Bluetooth Low Energy (BLE)-based wireless communication system, the
method comprising: configuring a BLE-based data packet to include
identification information indicating that the audio data is
included in a payload of the BLE-based data packet, wherein the
BLE-based data packet comprises a header and the payload, and the
payload comprises a payload header; and transmitting the BLE-based
data packet to at least one slave device, wherein the
identification information is included in compressed header
information of a Logical Link Control and Adaptation Protocol
(L2CAP) layer, which is the payload header in the payload of the
BLE-based data packet, and wherein the compressed header
information of the L2CAP layer has a length of one octet and
includes 1-bit length information indicating that the audio data is
included in the payload and 7-bit length information indicating a
length of the audio data.
2. The method of claim 1, wherein the identification information is
information relating to one bit being assigned to the BLE-based
data packet.
3. The method of claim 1, wherein if the BLE-based data packet does
not include the audio data, the BLE-based data packet includes an
L2CAP header that includes a length field of two octets and a
channel identifier (CID) field of two octets.
4. The method of claim 1, wherein the identification information is
included in the BLE-based data packet, and wherein the
identification information is used in a multiplexing layer to
indicate whether the audio data is included in the payload of the
BLE-based data packet.
5. The method of claim 4, wherein the identification information is
located in front of or at an end of the payload of the BLE-based
data packet, or is located between separated payloads of the
BLE-based data packet.
6. The method of claim 1, wherein if the BLE-based data packet
includes the audio data, the payload of the BLE-based data packet
includes a first payload and a second payload, which are separated
from each other, and the compressed L2CAP header information is
located between the first payload and the second payload.
7. The method of claim 6, wherein the L2CAP header information is
located in a first octet of a field including channel identifier
(CID) information, which is located in an existing header structure
of the L2CAP layer of the BLE-based data packet.
8. The method of claim 1, wherein the master device supports a
Hearing Aid (HA).
9. A master device for use in a Bluetooth Low Energy (BLE)-based
wireless communication system, the master device comprising: a
communication interface configured to perform BLE-based
communication with at least one slave device; and a controller
configured to configure a BLE-based data packet to include
identification information indicating that audio data is included
in a payload of the BLE-based data packet, and transmit the
BLE-based data packet to the at least one slave device, wherein the
BLE-based data packet comprises a header and the payload, and the
payload comprises a payload header, wherein the identification
information is included in compressed header information of a
Logical Link Control and Adaptation Protocol (L2CAP) layer, which
is the payload header in the payload of the BLE-based data packet,
and wherein the compressed header information of the L2CAP layer
has a length of one octet and includes 1-bit length information
indicating that the audio data is included in the payload and 7-bit
length information indicating a length of the audio data.
10. The master device of claim 9, wherein the identification
information is information relating to one bit being assigned to
the BLE-based data packet.
11. The master device of claim 9, wherein if the BLE-based data
packet does not include the audio data, the BLE-based data packet
includes an L2CAP header that includes a length field of two octets
and a channel identifier (CID) field of two octets.
12. The master device of claim 9, wherein the identification
information is included in the BLE-based data packet, and wherein
the identification information is used in a multiplexing layer to
indicate whether the audio data is included in the payload of the
BLE-based data packet.
13. The master device of claim 12, wherein the identification
information is located in front of or at the end of the payload of
the BLE-based data packet, or is located between separated payloads
of the BLE-based data packet.
14. The master device of claim 9, wherein if the BLE-based data
packet includes the audio data, the payload of the BLE-based data
packet includes a first payload and a second payload, which are
separated from each other, and the compressed L2CAP header
information is located between the first payload and the second
payload.
15. The master device of claim 14, wherein the L2CAP header
information is located in a first octet of a field including
channel identifier (CID) information, which is located in an
existing header structure of the L2CAP layer of the BLE-based data
packet.
16. The master device of claim 9, wherein the master device
supports a Hearing Aid (HA).
17. A method for receiving audio data by a slave device in a
Bluetooth Low Energy (BLE)-based wireless communication system, the
method comprising: receiving a BLE-based data packet from a master
device; and determining that data included in a payload of the
BLE-based data packet is the audio data based on identification
information included in the received BLE-based data packet, wherein
the BLE-based data packet comprises a header and the payload, and
the payload comprises a payload header, wherein the identification
information is included in compressed header information of a
Logical Link Control and Adaptation Protocol (L2CAP) layer, which
is the payload header in the payload of the BLE-based data packet,
and wherein the compressed header information of the L2CAP layer
has a length of one octet and includes 1-bit length information
indicating that the audio data is included in the payload and 7-bit
length information indicating a length of the audio data.
18. The method of claim 17, wherein the identification information
is information of relating to one bit being assigned to the
BLE-based data packet.
19. The method of claim 17, wherein if the BLE-based data packet
does not include the audio data, header information of the
BLE-based data packet is an L2CAP header that includes a length
field of two octets and a channel identifier (CID) field of two
octets.
20. The method of claim 17, wherein the identification information
is included in the BLE-based data packet, and wherein the method
further comprises determining whether the audio data is included in
the payload based on the identification information in the L2CAP
layer.
21. The method of claim 20, wherein the identification information
is located in front of or at the end of the payload of the
BLE-based data packet, or located between separated payloads of the
BLE-based data packet.
22. The method of claim 17, wherein if the BLE-based data packet
includes the audio data, the payload of the BLE-based data packet
includes a first payload and a second payload, which are separated
from each other, the identification information is included in the
compressed header information of the L2CAP layer of the BLE-based
data packet, and the compressed L2CAP header information is located
between the first payload and the second payload.
23. The method of claim 22, wherein the L2CAP header information is
located in a first octet of a field including channel identifier
(CID) information, which is located in an existing header structure
of the L2CAP layer.
24. The method of claim 17, wherein the slave device supports a
Hearing Aid (HA).
25. A slave device in a Bluetooth Low Energy (BLE)-based wireless
communication system, the slave device comprising: a communication
interface configured to perform BLE-based communication with a
master device; and a controller configured to receive a BLE-based
data packet from the master device, and determine that data
included in a payload of the BLE-based data packet is the audio
data based on identification information included in the received
BLE-based data packet, wherein the BLE-based data packet comprises
a header and the payload, and the payload comprises a payload
header, wherein the identification information is included in
compressed header information of a Logical Link Control and
Adaptation Protocol (L2CAP) layer, which is the payload header in
the payload of the BLE-based data packet, and wherein the
compressed header information of the L2CAP layer has a length of
one octet and includes 1-bit length information indicating that the
audio data is included in the payload and 7-bit length information
indicating a length of the audio data.
26. The slave device of claim 25, wherein the identification
information is information of relating to one bit being assigned to
the BLE-based data packet.
27. The slave device of claim 25, wherein if the BLE-based data
packet does not include the audio data, header information of the
BLE-based data packet is an L2CAP header that includes a length
field of two octets and a channel identifier (CID) field of two
octets.
28. The slave device of claim 25, wherein the identification
information is included in the BLE-based data packet, and wherein
the controller is further configured to determine whether the audio
data is included in the payload based on the identification
information in the L2CAP layer.
29. The slave device of claim 28, wherein the identification
information is located in front of or at the end of the payload of
the BLE-based data packet, or located between separated payloads of
the data payload.
30. The slave device of claim 25, wherein if the BLE-based data
packet includes the audio data, the payload of the BLE-based data
packet includes a first payload and a second payload, which are
separated from each other, and the compressed L2CAP header
information is located between the first payload and the second
payload.
31. The slave device of claim 30, wherein the L2CAP header
information is located in a first octet of a field including
channel identifier (CID) information, which is located in an
existing header structure of the L2CAP layer, and wherein the first
payload has a length of two octets.
32. The slave device of claim 25, wherein the slave device supports
a Hearing Aid (HA).
33. A System on Chip (SoC), the SoC comprising: a hardware
communication interface circuit configured to perform Bluetooth Low
Energy (BLE)-based communication with at least one slave device;
and a hardware controller circuit configured to configure a
BLE-based data packet to include identification information
indicating that audio data is included in a payload of the
BLE-based data packet, and transmit the BLE-based data packet to
the at least one slave device, wherein the BLE-based data packet
comprises a header and the payload, and the payload comprises a
payload header, wherein the identification information is included
in compressed header information of a Logical Link Control and
Adaptation Protocol (L2CAP) layer, which is the payload header in
the payload of the BLE-based data packet, and wherein the
compressed header information of the L2CAP layer has a length of
one octet and includes 1-bit length information indicating that the
audio data is included in the payload and 7-bit length information
indicating a length of the audio data.
34. A System on Chip (SoC), the SoC comprising: a hardware
communication interface circuit configured to perform Bluetooth Low
Energy (BLE)-based communication with a master device; and a
hardware controller circuit configured to receive a BLE-based data
packet from the master device, and determine that data included in
a payload of the BLE-based data packet is the audio data based on
identification information included in the received BLE-based data
packet, wherein the BLE-based data packet comprises a header and
the payload, and the payload comprises a payload header, wherein
the identification information is included in compressed header
information of a Logical Link Control and Adaptation Protocol
(L2CAP) layer, which is the payload header in the payload of the
BLE-based data packet, and wherein the compressed header
information of the L2CAP layer has a length of one octet and
includes 1-bit length information indicating that the audio data is
included in the payload and 7-bit length information indicating a
length of the audio data.
Description
BACKGROUND
1. Field of the Disclosure
The present disclosure relates generally to a method and apparatus
for transmitting and receiving data in a wireless communication
system, and more particularly, to a method and apparatus for
transmitting and receiving data in a Bluetooth Low Energy
(BLE)-based wireless communication system.
2. Description of the Related Art
Bluetooth is a technology standard for Personal Area Network (PAN),
which was developed in 1994, and is used to implement short-range
wireless communication between various wireless devices such as
mobile terminals and laptop computers. Bluetooth Special Interest
Group (SIG), which is a standard organization in charge of the
Bluetooth technology, has proposed the Bluetooth 4.0 specification
that includes Bluetooth Low Energy (BLE) as Bluetooth low energy
technology, and the Bluetooth standard has now reached the
Bluetooth 4.2 specification. The BLE is technology that enables
data communication with low power in Bluetooth.
FIG. 1 illustrates a protocol stack of BLE. For more details of the
BLE protocol, reference may be made to the Bluetooth 4.2
specification, which is incorporated herein by reference.
Referring to FIG. 1, in BLE, Logical Link Control and Adaptation
Protocol (L2CAP) layers 109 and 113 are used for mediation and
arbitration between controllers (e.g., a Bluetooth basic Rate
(BR)/Enhanced Data Rate (EDR) controller and a Low Energy (LE)
controller) that are responsible for data processing in an upper
layer protocol (e.g., a Service Discovery Protocol (SDP) layer 101,
a Generic Access Profile (GAP) 103, a Radio Frequency Communication
(RFCOMM) layer 105 and a Generic Attribute Profile (GATT) 107) and
a lower layer protocol (e.g., a link layer, a Media Access Control
(MAC) layer and a Physical (PHY) layer). If data is delivered from
the upper layer protocol, the L2CAP layers 109 and 113 may mediate
the delivered data, configure and manage each data for each logical
channel, and deliver the configured data to the controllers (e.g.,
the BR/EDR controller and the LE controller). The logical channel
refers to a channel that is established for the data delivered from
the upper layer protocol of the L2CAP layers 109 and 113, or from
an application.
In FIG. 1, the L2CAP layers 109 and 113 have low overhead so that
the L2CAP layers 109 and 113 may be ported, even in the
resource-limited host, such as various mobile terminals. The main
role of the L2CAP layers 109 and 113 is protocol multiplexing, and
segmentation and reassembly of the data delivered between the upper
layer protocol and the lower layer protocol may also be performed
in the L2CAP layers 109 and 113. The L2CAP layers 109 and 113 may
perform even the tasks related to Quality of Service (QoS) or
grouping during piconet configuration. The SDP layer 101 is a
protocol for exchanging information indicating which service is
available in a connected Bluetooth device and information about the
available service. The GAP 103 is a protocol for providing services
such as device discovery, connection models, security,
authentication, association models and service search, to Bluetooth
devices. The RFCOMM layer 105 may serve to emulate a serial
port.
In FIG. 1, Asynchronous Connection-oriented Link (ACL) layers 115
and 119 may provide an asynchronous data communication path, and a
Synchronous Connection-Oriented (SCO) layer 117 may be connected to
a voice layer 111 to provide a synchronous data communication
path.
In FIG. 1, the BR/EDR controller may include a link manager 121 and
a link controller 125, and the LE controller may also include a
link manager 123 and a link controller 127. The link managers 121
and 123 are responsible for creating, modifying and releasing
logical links, and for updating parameters related to physical
links between Bluetooth devices. The link controllers 125 and 127
are responsible for encoding and decoding Bluetooth packets from a
data payload, and for encoding and decoding of parameters related
to a physical channel, a logical transmission and a logical link.
In addition, the link controllers 125 and 127 may perform link
control protocol signaling.
However, the above-described BLE does not support transmission of
audio data. Therefore, there is a need for a packet structure for
supporting transmission of audio data even in the BLE.
SUMMARY
The present disclosure has been made to address at least the
above-mentioned problems and/or disadvantages and to provide at
least the advantages described below. Accordingly, an aspect of the
present disclosure is to provide a method and apparatus for
efficiently transmitting and receiving audio data in a BLE-based
wireless communication system.
Another aspect of the present disclosure is to provide a method and
apparatus for reducing overhead of a packet carrying audio data in
a BLE-based wireless communication system.
In accordance with an aspect of the present disclosure, there is
provided a method for transmitting audio data by a master device in
a Bluetooth Low Energy (BLE)-based wireless communication system.
The method includes configuring a data packet to include
identification information indicating whether the audio data of the
data packet is included in a payload and transmitting the data
packet to at least one slave device.
In accordance with another aspect of the present disclosure, there
is provided a master device in a Bluetooth Low Energy (BLE)-based
wireless communication system. The master device includes a
communication interface configured to perform BLE-based
communication with at least one slave device and a controller
configured to configure a data packet to identification information
indicating whether audio data of the data packet is included in a
payload and transmit the data packet to the at least one slave
device.
In accordance with another aspect of the present disclosure, there
is provided a method for receiving audio data by a slave device in
a Bluetooth Low Energy (BLE)-based wireless communication system.
The method includes receiving a BLE-based data packet from a master
device and determining whether data included in a payload of the
data packet is the audio data based on identification information
included in the received data packet.
In accordance with another aspect of the present disclosure, there
is provided a slave device in a Bluetooth Low Energy (BLE)-based
wireless communication system. The slave device includes a
communication interface configured to perform BLE-based
communication with a master device and a controller configured to
receive a BLE-based data packet from the master device and
determine whether data included in a payload of the data packet is
the audio data based on identification information included in the
received data packet.
As described herein, a structure of a new BLE data packet with
which an L2CAP layer of the BLE protocol transmits audio data is
provided. Specifically, an L2CAP header of a BLE data packet, which
is defined in the BLE standard, is compressed to distinguish
between a data Protocol Data Unit (PDU) of a data channel including
audio data and a data PDU of another channel. More specifically, an
identifier including identification information is used to indicate
whether audio data is included in a payload of the BLE data packet.
The BLE data packet for transmission of audio data may reduce
overhead of a BLE data packet. As a result, an air packet size of
the BLE data packet that is actually transmitted may be reduced,
thereby contributing to a reduction in power consumption of a
master device and/or a slave device.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other aspects, features and advantages of certain
embodiments of the present disclosure will be more apparent from
the following description taken in conjunction with the
accompanying drawings, in which:
FIG. 1 is a diagram illustrating a protocol stack of BLE;
FIG. 2 is a diagram illustrating devices that transmit and receive
BLE data packets with each other in a master-slave manner in a
BLE-based wireless communication system, according to an embodiment
of the present disclosure;
FIG. 3 is a diagram illustrating a known structure of a BLE data
packet defined in the Bluetooth SIG core specification;
FIG. 4 is a diagram illustrating a structure of an identifier
including identification information indicating whether audio data
is included in a payload in a BLE-based wireless communication
system, according to an embodiment of the present disclosure;
FIGS. 5A and 5B are diagrams illustrating an operation of an L2CAP
layer that uses an L2CAP header compressed by using an identifier
including identification information indicating whether audio data
is included in a payload in a BLE-based wireless communication
system, according to an embodiment of the present disclosure;
FIG. 6 is a diagram illustrating a structure of a BLE data packet
in a BLE-based wireless communication system, according to an
embodiment of the present disclosure;
FIGS. 7A and 7B are diagrams illustrating another structure of an
L2CAP header compressed by using an identifier including
identification information indicating whether audio data is
included in a payload in a BLE-based wireless communication system,
according to an embodiment of the present disclosure;
FIG. 8 is a diagram illustrating another structure of a BLE data
packet in a BLE-based wireless communication system, according to
an embodiment of the present disclosure;
FIG. 9 is a flowchart illustrating a method for transmitting audio
data by a master device in a BLE-based wireless communication
system, according to an embodiment of the present disclosure;
FIG. 10 is a flowchart illustrating a method for receiving audio
data by a slave device in a BLE-based wireless communication system
according to an embodiment of the present disclosure; and
FIG. 11 is a diagram illustrating a configuration of a device in a
BLE-based wireless communication system according to an embodiment
of the present disclosure.
Throughout the drawings, like reference numerals will be understood
to refer to like parts, components, and structures.
DETAILED DESCRIPTION
The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
the embodiments of the disclosure as defined by the claims and
their equivalents. It includes various specific details to assist
in that understanding but these are to be regarded as merely
examples. Accordingly, those of ordinary skilled in the art will
recognize that various changes and modifications of the embodiments
described herein can be made without departing from the scope and
spirit of the disclosure. In addition, descriptions of well-known
functions and constructions may be omitted for clarity and
conciseness.
The terms and words used in the following description and claims
are not limited to their dictionary meanings, but are merely used
to enable a clear and consistent understanding of the disclosure.
Accordingly, it should be apparent to those skilled in the art that
the following description of the embodiments of the present
disclosure is provided for illustrative purposes only and not for
the purpose of limiting the disclosure as defined by the appended
claims and their equivalents.
It is to be understood that the singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates
otherwise. Thus, for example, reference to "a component surface"
includes reference to one or more of such surfaces.
As defined herein, the term "substantially" means that the recited
characteristic, parameter, or value need not be achieved exactly,
but that deviations or variations, including for example,
tolerances, measurement error, measurement accuracy limitations and
other factors known to those of skill in the art, may occur in
amounts that do not preclude the effect the characteristic was
intended to provide.
FIG. 2 is a diagram illustrating devices that transmit and receive
BLE data packets with each other in a master-slave manner in a
BLE-based wireless communication system, according to an embodiment
of the present disclosure.
Referring to FIG. 2, in order to transmit audio data, a master
device 210 generates a BLE data packet having a structure of the
compressed L2CAP header and transmits the generated BLE data packet
to at least one slave device 230. The master device 210 and the
slave device 230 use a piconet scheme to establish a link, e.g., in
a master-slave manner, to communicate with each other. In the
piconet scheme, the master device 210 can configure a wireless
network with a plurality of slave devices to transmit and receive a
data packet to/from the slave devices. For example, in the field of
the technology in which low power consumption is required, such as
a Hearing Aid (HA) and the like, if the BLE data packet, which has
the structure of the compressed L2CAP header, is used, it is
possible not only to reduce power consumption of the slave device
230, but also to significantly increase the possible operating time
of the slave device 230. In the BLE technology, a device may be
referred to as a Low Energy (LE) device.
For a better understanding of the present disclosure, a structure
of the existing BLE data packet in the BLE technology will be first
described.
FIG. 3 is a diagram illustrating a structure of a BLE data packet
defined in the Bluetooth SIG core specification. This is a
structure of a BLE data packet that is defined in, for example,
Section 2.1, Vol 6. Part B, Bluetooth SIG Core Specification
version 4.2.
The BLE data packet 300 in FIG. 3 is a link layer packet format,
and the BLE data packet 300 includes a preamble 311, an access
address 313, a PDU 315, and a Cyclic Redundancy Check (CRC) 317.
The preamble 311 is used in a receiver (e.g., the slave device 230)
to perform frequency synchronization, symbol timing estimation and
Automatic Gain Controller (AGC) training and the like, and has a
length of 1 octet. The access address 313 is an address for
synchronization of a physical link and is used for distinguishing
each link. The access address 313 has a length of 4 octets. When
the packet 300 is transmitted in a physical data channel, the PDU
315 is a PDU of the data channel and has a length of 2 to 257
octets. The CRC 317 is used for error correction and has a length
of 3 octets.
In FIG. 3, the PDU 315 includes a PDU header 319, a PDU payload
321, and a Message Integrity Check (MIC) 323. The PDU header 319
includes 16 bits (i.e., 2 octets). The PDU payload 321 is a data
payload with a variable length. The MIC 323, which may be included
in the PDU 315 in the case of encrypted link layer connection, is
used for integrity check and has a length of 4 octets. In FIG. 3,
the PDU payload 321 includes an L2CAP header 325 and a payload 327.
The L2CAP header 325 includes a length field 325a of 2 octets and a
Channel Identifier (CID) field 325b of 2 octets. The L2CAP header
325 has a length of a total of 4 octets. The payload 327 may
include data that is received or delivered from/to the upper layer
protocol.
The overhead required in the existing structure for transmitting an
(encrypted) data packet, e.g., the BLE data packet 300 in FIG. 3,
is a total of 18 octets (144 bits)=preamble 311 (1 octet)+access
address 313 (4 octet)+PDU header 319 (2 octet)+L2CAP header 325 (4
octet)+MIC 323 (4 octet)+CRC 317 (3 octet), which is relatively
large with respect to data packets. Even in a case where the MIC
323 (4 octet) is not transmitted, the structure of the BLE data
packet 300 has an overhead of a total of 14 octets (112 bits).
Assuming that this BLE data packet structure has audio frame
duration of 10 ms and supports the sound quality of 32 kbps, a
required payload per packet of an audio stream is 320 bits. Thus,
the required payload corresponds to 31% (or 25.9% if the MIC 323 is
not transmitted) of the air packet size per (encrypted) BLE data
packet, so if the existing BLE data packet structure in FIG. 3 is
used, the power consumption by the overhead is considerable.
Therefore, in a case where a device, such as a Hearing Aid (HA),
whose key requirement is low power consumption, uses BLE, it is
important to reduce the overhead of the BLE data packet that is
transmitted and received by the device.
FIG. 4 is a diagram illustrating a structure of an identifier
including identification information indicating whether audio data
is included in a payload in a BLE-based wireless communication
system, according to an embodiment of the present disclosure. Using
this structure, it is possible to make an L2CAP header in which
overhead of is reduced when compared to the L2CAP header 325 shown
in FIG. 3.
Referring to FIG. 4, a compressed L2CAP header includes an
identifier field 401 of 1 bit and a length field 403 of 7 bits. The
L2CAP header in FIG. 4 is made by compressing the existing L2CAP
header 325 including the length field 325a of 2 octets and the CID
field 325b of 2 octets into an L2CAP header having a length of 1
octet, in terms of the length. If a BLE data packet is transmitted
using the compressed L2CAP header having the structure in FIG. 4,
the overhead may be reduced from the existing 144 bits to 120 bits,
so the ratio of the overhead to the air packet size may be reduced
from 31% to 27.3% (or from 25.9% to 21.6% if the MIC 323 is not
transmitted).
In the existing L2CAP header 325, the length field 325a of 2 octets
represents the length (or size) of the payload 327 except for the
length of the L2CAP header 325, and the CID field 325b of 2 octets
is used to identify a destination channel endpoint of the packet.
However, in the BLE standard supporting BLE and an HA, the L2CAP
layer of the protocol stack needs only to determine whether a
payload of the data packet is a payload of a data PDU including
audio data for the HA. Therefore, the 1-bit identifier field 401
used for determining whether data included in the payload is audio
data may be included in the L2CAP header, replacing the CID field
325b used in the existing L2CAP header 325.
If the slave device 230 in FIG. 2 is an HA, the maximum quality
used to support the HA is 64 kbps, and the maximum audio data
transmitted per packet is 640 bits, thus a total of 7 bits are used
for the length field 403 in FIG. 4. Therefore, given that the
packet is a BLE data packet carrying audio data, the existing L2CAP
header 325 of 4 octets may be compressed into the L2CAP header of 1
octet, as shown in the FIG. 4.
On the other hand, the 1-bit identifier field 401 may be used to
indicate/determine whether the data included in the payload is
audio data, by the L2CAP layers 109 and 113, which are used for
performing multiplexing in the Bluetooth protocol stack of FIG. 1.
As another example, it is also possible to configure the BLE data
packet so that identification information corresponding to the
1-bit identifier field 401 may be independently included therein,
regardless whether the L2CAP header is compressed or not. The
identification information may be included in the existing L2CAP
header, or in another specified position of the BLE data
packet.
FIGS. 5A and 5B are diagrams illustrating an operation of an L2CAP
layer that uses an L2CAP header compressed by using an identifier
including identification information indicating whether audio data
is included in a payload in a BLE-based wireless communication
system, according to an embodiment of the present disclosure.
FIG. 5A illustrates an L2CAP header having a length of 1 octet,
which is proposed in the example of FIG. 4, and is compressed by
using an identifier including identification information indicating
whether audio data is included in a payload.
Upon receiving a BLE data packet, a slave device supporting an HA
determines whether data included in a payload is audio data or data
of another channel, based on one Most Significant Bit (MSB) bit of
the L2CAP header following the PDU header. For example, if the
1-bit identifier field 401 (i.e., MSB) is set to `1`, as shown in
FIG. 5A, the slave device determines that the data included in the
payload of the BLE data packet is audio data, checks the size of
the audio data using the length field 403 following the 1-bit
identifier field 401, and delivers the determined audio data to the
audio layer 107 in the protocol stack of FIG. 1. If an identifier
field 501 (i.e., MSB) is set to `0`, as shown in FIG. 5B, the slave
device determines that the data included in the payload of the BLE
data packet as data of other channel, and performs an operation of
the existing L2CAP layer. In the case of FIG. 5B, since the data
included in the payload of the BLE data packet is not audio data,
the L2CAP header includes the 1-bit identifier field 501, a 15-bit
length field 503 indicating a length of data carried on the
payload, and a CID field 505 like the existing CID field 325b.
Alternatively, if the data included in the payload of the BLE data
packet is not audio data, it is also possible to use the existing
L2CAP header 325 intact.
For the above-described operation of the slave device, depending on
whether the data to be transmitted is audio data, a master device
supporting an HA may configure, if the data is audio data, a
compressed BLE data packet that includes, for example, the 1-bit
identifier field 401 that is set to `1` and the 7-bit length field
403 indicating a length of audio data carried on the payload, as
shown in FIG. 5A, and transmit the configured BLE data packet. If
the data to be transmitted is not audio data, the master device may
configure the L2CAP header as shown in FIG. 5B and transmit the
configured L2CAP header, or may transmit the existing L2CAP header
325.
FIG. 6 is a diagram illustrating a structure of a BLE data packet
in a BLE-based wireless communication system, according to an
embodiment of the present disclosure.
Similar to the BLE data packet 300 shown in FIG. 3, a BLE data
packet 600 in FIG. 6 includes a preamble 611, an access address
613, a PDU 615 and a CRC 617. Accordingly, a detailed description
of these components will be omitted. As described in the examples
of FIGS. 4-5B, if data included in a payload is audio data, the
L2CAP header 625 includes, for example, a 1-bit identifier field
401 that is set to `1` and a 7-bit length field 403 indicating a
length of its audio data. On the other hand, if the data included
in the payload is data of another channel, the L2CAP header 625 may
be configured to include, for example, a 1-bit identifier field 501
that is set to `0`, a 15-bit length field 503 and a CDI field 505,
or the existing L2CAP header 325 may be used.
In a case where the compressed L2CAP header is configured as in the
examples of FIGS. 4-5B, if the size of a data PDU of another
channel, which is not audio data for the HA, exceeds, for example,
128 bytes, a collision may occur between the identifier fields 401
and 501 of the compressed L2CAP header and the data of the another
channel, thereby causing a situation where it is not possible to
distinguish between the audio data and the data of the another
channel. In accordance with an embodiment of the present
disclosure, the L2CAP header may be compressed by using an
identifier including identification information indicating whether
audio data is included in a payload, thereby making it possible to
prevent the collision.
FIGS. 7A and 7B illustrate another structure of an L2CAP header
compressed by using an identifier including identification
information indicating whether audio data is included in a payload
in a BLE-based wireless communication system, according to an
embodiment of the present disclosure.
FIG. 7A illustrates a packet structure based on the existing BLE
standard, which includes a PDU header 701 of 2 octets, an L2CAP
header that includes a length field 703 of 2 octets and a CID 705
of 2 octets, a payload 707 and a CRC 709. These fields are the same
as their corresponding fields in FIG. 3, so a detailed description
thereof will be omitted. FIG. 7B illustrates a packet structure
including a compressed L2CAP header with another structure, wherein
the packet structure includes a PDU header 711, an L2CAP header 715
that includes a 1-bit identifier field 715a and a 7-bit length
field 715b. The packet structure is compressed using an identifier
including identification information indicating whether audio data
is included in a payload, a first payload 713 and a second payload
717. The compressed L2CAP header 715 that includes the 1-bit
identifier field 715a and the 7-bit length field 715b is the same
as the L2CAP header shown in FIG. 4, which is compressed by using
an identifier including identification information indicating
whether audio data is included in a payload.
As for the first payload 713 and the second payload 717, Table 2.2
in Section 2.1, Vol 3. Part A of Bluetooth SIG Core Specification
version 4.2 provides that in a CID used in a BLE logical link,
0x0080 to 0xFFFF for example are not used. Therefore, if the L2CAP
header 715 that is compressed by using an identifier including
identification information indicating whether audio data is
included in a payload is located in a first octet of the CID field
705 of the existing L2CAP header, (i.e., if the first payload 713
and the second payload 717 including audio data are located in both
sides of the L2CAP header 715 and compressed by using an identifier
including identification information indicating whether audio data
is included in a payload, as shown in FIG. 7B), it is possible to
prevent collision between audio data and data of another
channel.
FIG. 8 is a diagram illustrating another structure of a BLE data
packet in a BLE-based wireless communication system, according to
an embodiment of the present disclosure. The BLE data packet 800
shown in FIG. 8 illustrates where the L2CAP header 715 is
compressed by using an identifier including identification
information indicating whether audio data is included in a payload,
as shown in FIG. 7B.
The BLE data packet 800 in FIG. 8, like the BLE data packet 300 in
FIG. 3, includes a preamble 811, an access address 813, a PDU 815
and a CRC 817. Accordingly, a detailed description of these
components will be omitted. In a separated configuration of first
and second payloads 825 and 829, the first payload 825 may have a
length of, for example, 2 octets. As described in the examples of
FIGS. 4-5B, if data included in a payload is audio data, the L2CAP
header 827 may include, for example, a 1-bit identifier field 401
that is set to `1` and a 7-bit length field 403 indicating a length
of its audio data. On the other hand, if the data included in the
payload is data of another channel, an L2CAP header may be
configured as shown in FIG. 5B, or the existing L2CAP header 325
may be used.
FIG. 9 is a flowchart illustrating a method for transmitting audio
data by a master device in a BLE-based wireless communication
system, according to an embodiment of the present disclosure.
Referring to FIG. 9, in step 901, the master device configures a
data packet including identification information indicating whether
audio data is included in a payload of a BLE-based data packet. In
step 903, the master device transmits the data packet to at least
one slave device.
FIG. 10 is a flowchart illustrating a method for receiving audio
data by a slave device in a BLE-based wireless communication
system, according to an embodiment of the present disclosure.
Referring to FIG. 10, in step 1001, the slave device receives a
BLE-based data packet. In step 1003, the slave device determines
whether data include in a payload is audio data, based on the
identification information included in the received data packet,
and receives the audio data depending on the determination
result.
FIG. 11 is a block diagram illustrating a configuration of a device
in a BLE-based wireless communication system, according to an
embodiment of the present disclosure. The device configuration in
FIG. 11 may be applied to each of the master device and the slave
device.
Referring to FIG. 11, a controller 1110 controls transmitting or
receiving of a BLE data packet including audio data depending on
the BLE data packet structure and a data transmission/reception
method according to an embodiment of the present disclosure, which
have been described in the examples of FIGS. 2 to 10. A
communication interface 1130 includes a communication module for
performing BLE-based data transmission/reception with a counterpart
device (e.g., a master device or a slave device).
The aforementioned components of the master and slave devices,
which are configured to perform the steps of the methods described
above, can be implemented using hardware (e.g., electrical
circuitry), software (e.g., various modules) and a combination
thereof. Moreover, the components can be provided on one and/or
multiple layers of a System on Chip (SoC).
While the present disclosure has been shown and described with
reference to certain embodiments thereof, it should be understood
by those skilled in the art that many variations and modifications
of the method and apparatus described herein will still fall within
the scope of the present disclosure as defined in the appended
claims and their equivalents.
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